1. Field of the Invention
This invention relates to the field of electric motors and specifically to electric motors that are capable of both linear and rotary motion.
2. Description of the Related Art
Electric motors including dc stepper motors have been utilized in many applications. Some of these applications have included those where the electric motors have been subjected to vibration shock and other external forces. Unfortunately, due to the nature of electric motors, it has not been possible to prevent external forces from causing the rotation of the motor shaft. Consequently, there is a need for an electric motor that is prevented from rotating until energized.
The present invention solves the problem discussed above and is a motor capable of both axial/linear displacement and rotation. This motor uses one coil to translate the motor along its axis for linear motion and a second coil to cause the shaft to rotate. Coacting with the translate coil is a translate magnet where the north and south poles are oriented along the motor shaft. A segmented magnet where alternating north and south poles are located along the periphery of the magnet is used to interact with the second or rotational coil so that the interaction of the magnetic field of the segmented magnet and the magnetic field produced by the rotation coil causes the rotary magnet to rotate. Rotation of the rotary magnet, which cooperates with the shaft to which it is operably connected, causes rotation of the motor shaft. To prevent rotation of the motor shaft a key or keyed gear is operably connected to the shaft. This key or keyed gear fits into a detent in the motor casing of an appropriate size and shape or an external detent of an appropriate size and shape. By energizing the translate coil the motor shaft and key or keyed gear is removed from the detent in the casing or external detent so that energizing the rotate coil may cause the rotation magnet and shaft to rotate. The key and its associated detent are designed to limit and/or prevent rotation of the shaft when the key is resting in the detent. Consequently, a motor of this invention would not rotate under the imposition of an external force unless the translate coil was energized.